Quantum Triple Point and Quantum Critical End Points in Metallic Magnets

Area of Science:

• Condensed matter physics
• Quantum magnetism

Background:

• Ferromagnetic (FM) and antiferromagnetic (AFM) orders are fundamental in low-temperature metallic magnets.
• Classical magnet phase diagrams describe the coexistence and transitions between these magnetic orders.

Purpose of the Study:

• To investigate the impact of universal quantum effects on the phase diagrams of metallic magnets.
• To understand how quantum phenomena modify the regions of concurrent FM and AFM order and the nature of magnetic transitions.

Main Methods:

• Theoretical analysis of magnetic systems incorporating quantum effects.
• Phase diagram mapping under varying conditions, including the presence of a magnetic field.

Main Results:

• Quantum effects qualitatively alter classical magnet phase diagrams.
• The region of concurrent FM and AFM order is reduced.
• Several magnetic transitions change from second-order to first-order.
• A quantum triple point or a quantum critical end point emerges in a magnetic field.

Conclusions:

• Universal quantum effects play a crucial role in shaping the low-temperature phase diagrams of metallic magnets.
• These quantum effects lead to novel phase behaviors, including new types of critical points.